Thienylthio-substituted aldehydes and ketones and mineral oils containing the same



llnite John W. Brooks, Wenonah, N. 3., assignor to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. Application August 31, 1950, Serial No. 182,639

9 Claims. (Cl. 25248.2)

This invention relates to a new class of chemical compounds and to mineral lubricating oils containing these compounds. More particularly, the invention relates to thienylthio-substituted aldehydes and ketones and to mineral lubricating oil compositions containing these compounds as oxidation and corrosion inhibitors.

As is well known, mineral lubricating oils tend to decompose, especially under heat and oxidizing conditions, such as those encountered in use in internal combustion engines. The decomposition products formed in the oil are acidic in nature and exert a corrosive action upon the metal surfaces being lubricated. The present invention is concerned with a novel class of chemical compounds which are highly effective in counteracting this tendency of an oil to decompose and thus harm the metal surfaces.

In accordance with this invention it has been found that thienylthio-substituted aldehydes and ketones are excellent addition agents for stabilizing mineral lubricating oils against the deleterious elfects of oxidation. It is, therefore, the primary object of this invention to provide lubricating oil compositions containing these new antioxidant compounds. Other' and further objects will become apparent as the description of the invention proceedsp The thienylthio-substituted aldehydes and ketones of the invention are made by reacting a thiophenethiol, such as Z-thiophenethiol or 3-thiophenethiol, withunsasaturated or chlorinated aldehydes and ketones having from 2 to about 36 aliphatic carbon atoms. The unsaturated aldehydes and ketones contemplated herein are specifically those in which the unsaturation is olefinic in character, i. e. as opposed to aromatic and heterocyclic unsaturation. Thus, although the aldehydes and ketones contemplated herein, i. e. those having one or more olefinic double bonds, may also contain substituent groups of an aromatic or heterocyclic character, these latter groups do not take part in the reaction with thiophenethiol. Correspondingly, the chlorinated aldehydes and ketones contemplated herein are those in which the chlorine atoms are attached to aliphatic carbon atoms and not to aromatic or heterocyclic carbons, although these compounds may also contain substituent groups of this latter character. The suitable unsaturated compounds, therefore, will contain at least one and generally from 1 to 6 olefinic bonds while the chloro-compounds may have at least one chlorine atom and usually from 1 to about 6 chlorine atoms joined to aliphatic carbon atoms.

As non-limiting examples of the chlorinated aldehydes and ketones and unsaturated aldehydes and ketones contemplated for use in this invention the following may be mentioned:

(a) Chlorinated aldehydes, such as chloroacetaldehyde, dichloropropionaldehyde, chloral, chlorocaprylic aldehyde, chlorolauric aldehyde, chloropalmitic aldehyde and chlorotetracosonaldehyde.

(b) Chlorinated ketones, such as chloroacetone, a1

"*itates Patent 2,721,179 Patented Oct. 18, 1955 pha-dichloroacetone, chloromethyl phenyl ketone, alphachloro-alpha-phenyl dimethyl ketone, alpha-chloro-alphathienyl dimethyl ketone, chlorobutyl amyl ketone, chlorocyclohexyl acetone, dichlorododecyl ketone and chlorooctyl hexadecyl ketone.

(c) Unsaturated aldehydes, such as acrolein, tiglic aldehyde, crotonic aldehyde, citronellal and oleic aldehyde, and

(d) Unsaturated ketones, such as vinyl methyl ketone, allyl ethyl ketone, benzal acetone, phorone, dodecenyl ketone and ionone.

The reaction between the unsaturated, or chlorinated, aldehyde or ketone and the thiophenethiol is readily carried out by heating the reactants together at moderately elevated temperatures, i. e. between about 50 C. and about 150 C. for several hours, usually from about 1 to about 5 hours. In the case of the chlorinated aldehydes and ketones the reaction is conducted in the presence of an alkali, such as potassium hydroxide, which serves to neutralize the hydrogen chloride formed in the reaction. With respect to the unsaturated aldehydes and ketones, it has been found that, generally, the reaction occurs most readily with those in which the olefinic bonds appear at the alpha, beta position (i. c. with respect to the carbonyl group). However, in the case of the compounds Where the olefinic bonds are otherwise located, the reaction may be made more efficient by utiiizing somewhat higher reaction temperatures than indicated above, i. e. temperatures of from C. to 300 C. The use of a catalyst, such as silica-alumina, is also advantageous with these compounds.

The unsaturated aldehyde or ketone is generally reacted with a sufficient amount of thiophenethiol to satisfy the olefinic unsaturation thereof, although lesser amounts may be used if a completely substituted product is not especially desired. Thus, as a rule, Where the aldehyde or ketone contains a single olefinic bond, one mol of the aldehyde or ketone is reacted with approximately one mold of the thiophenethiol. Correspondingly, with the chlorinated aldehydes and ketones one mol of thiophenethiol is generally utilized for each atomic proportion of chlorine in the chlorinated compound. Thus, where the aldehyde or ketone is monochlorinated, one mol of thiophenethiol per mol of the aldehyde or ketone is used. For a dichlorinated compound, two mols of thiophenethiol is ordinarily used, etc. The aldehydes and ketones which contain more than one olefinic bond, or more than one chlorine atom, yield polythienylthio-substituted products. The olefinic unsaturation or chlorination in the case of the ketones may apear on both radicals attached to the carbonyl group. In the case of the chlorinated aldehydes and ketones, complete substitution of the chlorine atoms, or addition of thienylthio groups to all of the olefinic bonds, is not always necessary for the provision of products which are valuable as oil addition agents, particularly where the aldehydes and ketones are polychlorinated or polyunsaturated.

The following equations are typical of the reactions which occur when thiophenethiol is reacted with unsaturated aldehydes or ketones (Equation 1) and chlorinated aldehydes or ketones (Equation 11) of the type herein contemplated.

H S-CCHzO-CH3 l l] C t 3-thiophenethiol Benzal acetone ClCHzO-CH3 II O hloroacetone KOH 3-thienylthioacetone The compounds particularly contemplated by the invention will conform to one of the following general formulae:

3-thiophenethiol r-ta Y. O e

wherein X represents a thienylthio radical, R represents an aliphatic hydrocarbon residue, Y is selected from hydrogen, alkyl, aryl and heterocyclic radicals, a and b are integers from 1 to 6, whose total does not exceed 6, c is an integer from 1 to 3; the total number of aliphatic carbons in any one compound not exceeding about 36.

As illustrative of the thienylthio-substituted aldehydes and ketones contemplated by the invention, there may be mentioned the following:

Aldehydes:

Thienylthioacetaldehyde Dithienylthioacetaldehyde Alpha, beta-dithienylthiopropionaldehyde Beta trithienylthiopropionaldehyde Thienylthiocaprylaldehyde Thienylthiolauraldehyde Thienylthiopalmataldehyde Thienylthiotetraconsonaldehyde Beta-thienylthiopropionaldehyde Alpha-methyl-beta-thienylthiobutraldehyde Beta-thienylthiobutraldehyde Beta-methyl-theta-thienylthiooctaldehyde Iota-thienylthioheptadecylaldehyde Thienylthiotriacontronaldehyde Alpha, alpha-dithienylthiomelissaldehyde Alpha, alpha, gamma, gamma-tetrathienylpentatriacontonaldehyde Thienylthiohexacosanaldehyde Ketones:

Alpha-thienylthioacetone Alpha, alpha'-dithieny1thioacetone Thienylthiomethyl phenyl ketone Alpha-thienylthio, alpha-phenyldimethyl ketone Alpha-thienylthio, alphathienyldimethyl ketone Thienylthiobutyl amyl ketone Thienylthiocyclohexyl acetone Dithienylthiododecyl ketone Thienylthiooctyl hexadecyl ketone Alpha, alpha-dithienylthioethyl methyl ketone Beta-thienylthioethyl methyl ketone Gamma-thienylthiopropyl ethyl ketone Alpha, alpha'-dithienylthio, alpha-phenyldiethyl ketone Alpha, alpha-dithienylthiodiamyl ketone Alpha, alpha, beta, beta-tetrathienylthiodioctyl ketone Hexathienylthiodidodecyl ketone Thienylthiostearone Alpha, alpha, beta, beta'-tetrathienylthiopalmitone Alpha, alpha-dimethyl-beta, beta-dithienylthiostearophenone Hexathienylthiomyristone To further illustrate the means of preparing the thienylthio-substituted aldehydes and ketones contemplated herein, the following examples are presented.

EXAMPLE I Beta-phenyl-beta-3-thienylzhioethyl methyl ketone A solution of 110 grams mol) of benzal acetone in 300 cc. of benzene was placed in a 1 liter flask. Eighty-eight grams mol) of 3-thiophenethiol were then added. The temperature did not increase during the addition, so heat was applied gradually and the mixture stirred at 50 C. for 2 hours and then at 70 C. for 2 hours.

The reaction mixture was then topped to C. under mm. to remove benzene, and to C. at 1 mm. to remove unreacted thiophenethiol and benzal acetone. The liquid product thus obtained weighed 114 grams, which represents a yield of 57.6% of theoretical. The product analyzed 24.4% sulfur, as compared to the theoretical 22.83% for beta-phenyl, beta-3-thienylthioethyl methyl ketone.

EXAMPLE II 3-thienylthioacetone A mixture of 232 grams (2 mols) of 3-thiophenethiol and 112 grams (2 mols) of KOH dissolved in 200 cc. of water and 400 cc. of alcohol were added to a flask. To this mixture was added grams (2 mols) of chloroacetone at such a rate that the temperature stayed around 50 C. The reaction mixture was stirred at 70 C. for 3 hours after the addition was complete and then distilled under 0.3 mm. pressure. Two hundred fortythree grams of liquid product were collected between 100-125 C. The product analyzed 37.50% sulfur, as compared to the calculated value of 37.21% for 3- thienylthioacetone.

EXAMPLE III Beta-3-thienylthiobutyraldehyde Three hundred twenty-two grams (4 mols) of crotonaldehyde (87% solution) were placed in a 2 liter flask and 464 grams (4 mols) of 3-thiophenethiol added at such a rate that the temperature stayed between 45-50 C. The mixture was heated at 70 C. for 3 hours after addition was complete. The mixture was then distilled under 0.8 mm. and 470 grams of product were collected at 122:5 C. The product analyzed 34.27% sulfur, as compared to the calculated value of 34.43% for beta-3-thienylthiobutyraldehyde.

To demonstrate the efiectiveness of the products herein contemplated as lubricating oil additives, a number of comparative tests were conducted on mineral lubricating oils alone and these same oils blended with minor amounts of the several representative products shown in the preceding examples.

German tar test This test is designed to show the tendency of a lubricating oil to oxidize in use.

In this test, a sample of test oil (150 grams) is placed in a 250 ml. extraction flask equipped with a cork stopper and having a 6 mm. 1. D. inlet tube extending through this stopper to the bottom of the flask. The flask also has a vent tube. The flask is placed in a constant temperature bath and maintained at a temperature of 120 C. throughout the test. Oxygen is passed through the oil via the inlet tube at the rate of two bubbles per second for 70 hours.

The extent of oxidation efiected in the oil is reported in terms of the neutralization number (N. N.) thereof, as measured at the completion of the test. The higher the N. N. the greater the oxidation which took place, since the oxidized products formed. in oil arev known to be acidic in character. The results obtained with the blended oil are compared to the results obtained with the unblended oil in each case.

Table I shows the results obtained in this test with several of the compounds of the invention. The reference oil used in these tests was an acid refined coastal distillate having a Saybolt Universal viscosity of 69 seconds at 100 F.

Bubble test This test determines the efiectiveness of an oil in pre venting bearing corrosion. In this test, an accurately weighed quarter of a connecting rod bearing having a cadmium-silver alloy surface is placed in a 200 x 25 mm. test tube, together with 30 gms. of the test oil. A mm. glass inlet tube drawn down to about 1 mm. I. D. for about 30 mm. at one end is placed in the tube. The test tube is placed in a constant temperature bath, maintained at 175 C. and air blown through the test oil at a rate of 2 liters per hour for 22 hours. The test piece is then removed and reweighed. The results are reported in milligrams of bearing weight loss. The results obtained in this test with several of the compounds of the invention are shown in Table II. The reference oil used in these tests was an SAE 20 grade solvent-refined Pennsylvania neutral stock.

Lauson engine test An oil blend of beta-3-thienylthiobutyraldehyde (Ex ample III) was also subjected to an operation test in a single cylinder Lauson engine having copper-lead bearings. This test determines oil deterioration and the corrosiveness of the oil in use. The engine is run with an oil temperature of 270 F. and a jacket temperature of 212 F. at a speed of 1825 R. P. M. for 100 hours. The results are reported in milligrams of bearing weight loss, neutralization number (N. N.) of the oil and also the viscosity increase during the run. These results are oompared in a similar run on the blank oil. The results obtained are shown in Table III. The oil used was an SAE 20 grade solvent-refined Pennsylvania neutral stock.

As shown in Table III, the blended oil gave much improved results over the uninhibited oil.

The amounts of the compounds of the invention to be added to mineral lubricating oils generally will be from about 0.1 per cent to about per cent by weight depending upon the particular application for which the oil is designed.

agents for use in lubricating oils, it should be clear that they may also be utilized in other petroleum oil fractions in which antioxidant properties'are desired, such as gasolines, fuel oils and heavy lubricants, such as greases, etc.

The products of the invention may, of course, be used as lubricating oil, or other petroleum oil fractions, containing other additives designed to improve the character of such fractions in other respects, such as pour point depressants, detergents, extreme pressure agents, etc.

This invention is not intended to be limited in any way by the specific examples or illustrative procedures described herein, but only as indicated in the appended claims.

I claim:

1. A compound of the general formula selected from X..Ro-Rx and (b) X..R-0Y

wherein X represents a thienylthio radical, R represents an aliphatic hydrocarbon residue, Y represents a radical selected from hydrogen, alkyl and monocarbocyclic aryl radicals and a is an integer from 1 to 2, the total number of aliphatic carbon atoms in said compound not exceeding about 36.

2. The compound 3-thienylthioacetone.

3. The compound beta-3-thienylthiobutyraldehyde.

4. The compound beta-phenyl-beta-3-thienylthioethyl methyl ketone.

5. A mineral lubricating oil composition containing a major proportion of lubricating oil and a minor proportion, suflicient to inhibit said oil against oxidation, of a compound of the general formula selected from wherein X represents a thienylthio radical, R represents an aliphatic hydrocarbon residue, Y represents a radical selected from hydrogen, alkyl and monocarbocyclic aryl radicals and a is an integer from 1 to 2, the total number of aliphatic carbon atoms in said compound not exceeding about 36.

6. A mineral lubricating oil composition containing a major proportion of a lubricating oil and a minor proportion, sufiicient to inhibit said oil against oxidation, of the compound 3-thienylthioacetone.

7. A mineral lubricating oil composition containing a major proportion of a lubricating oil and a minor proportion, sufiicient to inhibit said oil against oxidation, of the compound beta-3-thienylthiobutyraldehyde.

8. A mineral lubricating oil composition containing a major proportion of a lubricating oil and a minor proportion, suflicient to inhibit said oil against oxidation, of the compound beta-phenyl-beta-3-thienylthioethyl methyl ketone.

9. A mineral lubricating oil concentrate containing V 7 from about 25 to about 75 per cent by weight of a compound ofthe general formula selected from wherein X represents a thienylthio radical, R represents an aliphatic hydrocarbon residue, Y represents a radical selected from hydrogen, alkyl and monocarbocyclic aryl radicals and a is an integer from I to 2, the total number of aliphatic carbon atoms in said compound not exceeding about 36.

UNITED STATES PATENTS Allen Oct. 21, 1941 Brooks et a1 Sept. 6, 1949 Sturgis et a1 Apr. 18, 1950 Lukasiewicz July 18, 1950 Lukasiewicz July 18, 1950 Brooks Sept. 19, 1950 Brooks et al. Dec. 19, 1950 Brooks et a1. July 24, 1951 OTHER REFERENCES Organic Chem, Gilman, Wiley, 1938, vol. 1, page 62. 

1. A COMPOUND OF THE GENERAL FORMULA SELECTED FROM 